Voltage waveform distortion in synchronous generators with rectifier loading

Armature voltage waveforms of synchronous generators with bridge rectifier loads are distorted to a degree determined by the generator transient (or subtransient) inductances. A generator with zero transient saliency (z.t.s.) has a true sinusoidal waveform, apart from commutation disturbances occurring four times a cycle. The disturbance level is reduced by decreasing the generator transient inductance. Reduced waveform distortion becomes important when the generator is loaded with parallel d.c./a.c. loads and when the a.c. load is sensitive to waveform harmonics. A z.t.s. generator is recommended for such mixed-load applications. The operating equations for the z.t.s. generator have been simplified from previous work and performance predictions are readily made. To some extent, the behaviour of a z.t.s. generator with a rectifier load closely resembles simple constant-source-inductance rectifier operation. Some experimental results are given for a cylindrical-rotor z.t.s. generator and for a salient pole generator with two different damper winding arrangements.